jquery document ready example
jquery
HTML
<section class="item-form">
<div class="row">
<div class="col-lg-2 col-md-6">
<label for="quanty-0">Quanty</label>
<input class="need-to-dup" type="text" name="quanty-0" value="" >
</div>
<div class="col-lg-4 col-md-6">
<label for="item-0">Item</label>
<input class="need-to-dup" type="text" name="item-0" value="" >
</div>
<div class="col-lg-4 col-md-6">
<label for="comment-0">Comment</label>
<input class="need-to-dup" type="text" name="comment-0">
</div>
<div class="col-lg-2 col-md-6">
<label for="remove-0">Remove</label>
<button class="need-to-dup remove-item-button btn-block btn-outline-secondary" type="button" name="remove-0">
<i class="fa fa-trash-o" aria-hidden="true"></i>
</button>
</div>
</div>
<div class="add-item">
<p>Add Another Item</p>
</div>
</section>
JavaScript
$(document).ready(function(){
$(".add-item").on("click", function() {
var rows = $(".row","section.item-form"),
first = rows.first(), last = rows.last(), clone = first.clone();
console.log(first);
clone.insertAfter(last).find("[name!=''][name]").each(function() {
var name = $(this).attr("name").split("-")[0];
$(this).siblings("label").attr("for", name + "-" + rows.length);
$(this).attr("name", name + "-" + rows.length);
});
});
});